Field of the Disclosure
The present disclosure, for example, relates to wireless communications systems, and more particularly to cooperative use of wireless wide area network (WWAN) and wireless local area network (WLAN) components in a single device.
Description of Related Art
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, space and power). Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems.
By way of example, a wireless multiple-access communication system may include a number of base stations or access points, each simultaneously supporting communication for multiple communication devices, otherwise known as user equipment (UEs), wireless terminals or stations (STAs). A base station or access point may communicate with UEs or STAs on downlink channels (e.g., for transmissions from a base station/access point to a UE/STA) and uplink channels (e.g., for transmissions from a UE/STA to a base station/access point). Communication between a UE and a base station may use a WWAN, while communication between a STA and an access point may use a WLAN. Wi-Fi is an example of a common WLAN technology supported by a STA. In the following, communication devices that communicate using both WWAN and WLAN may be generically referred to as a UE.
UEs typically include different WWAN and WLAN radios. The WWAN and WLAN radio subsystems may be driven by reference clocks generated by different oscillators. Each reference clock may have different frequencies and frequency errors. Thus, when a UE application shares both WWAN and WLAN resources, the different frequencies and frequency errors of the different radio subsystems may result in additional errors. Conventional methods for estimating and correcting a frequency offset between the different reference clocks of WWAN and WLAN subsystems may be complex and add latency to the system.